In recent years, the development of a surface illumination apparatus and an image display using a light source constituted by semiconductor material, such as a light emitting diode (LED) and laser, which does not contain mercury and has low power consumption is being promoted in terms of environmental issues and power saving.
There is a liquid crystal display as an example of image displays. A liquid crystal display uses a liquid crystal panel as a spatial modulation device, and forms images by illuminating from the rear face of the liquid crystal panel using a surface illumination apparatus (backlight), and spatially modulating the transmitted light. Available methods used for decreasing power consumption of the liquid crystal display are a method of aligning lights emitted from the backlight into single polarized lights, or a method of illuminating each sub-pixel of red, green and blue constituting the liquid crystal panel with incident light which is separated into a corresponding color (wavelength).
For example, a configuration of aligning the polarizing directions of lights to enter the light guiding plate, by allowing the laser beams emitted from the laser light source transmit through a plurality of rows of polarizing prisms, has been disclosed (e.g. Patent Document 1). Since the polarizing directions of the laser beams emitted from the principal plane of the light guiding plate can be aligned by this configuration, a liquid crystal display of which power consumption is low can be implemented.
Another example is a configuration of aligning the polarizing components of lights emitted from the light guiding plate in a predetermined direction by allowing the lights from the LED light sources, disposed on the side face of a light guiding plate, to enter into the light guiding plate and forming micro-slits, as polarization change means, on the rear face of the light guiding plate (e.g. Patent Document 2). By this configuration, lights having polarizing components in a predetermined direction can be emitted even if an LED is used for the light source, and a liquid crystal display of which power consumption is low can be implemented.
Another configuration proposed is a configuration of allowing white lights from the LED light sources, disposed on the side face of a light guiding plate, to enter into the light guiding plate, wherein an interference filter which reflects the lights in a predetermined wavelength range and transmits the lights in the rest of the wavelength range, is disposed (e.g. Patent Document 3). By separating the entered white lights into red, green and blue, and illuminating the liquid crystal panel in this way, the lights can be efficiently used, whereby the liquid crystal display of which power consumption is low can be implemented.
Other than these examples, many examples of surface illumination apparatuses, in which a predetermined area is illuminated by a predetermined color of light, are seen in our daily lives, such as a route guiding plate and traffic light used on roadways.
In the above mentioned prior art, however, light utilization efficiency is high but the configuration of the optical system is complicated, therefore manufacturing the apparatus is not easy, and the cost of the surface illumination apparatus and liquid crystal display becomes high.    Patent Document 1: Japanese Patent Application Laid-open No. 2008-277279    Patent Document 2: Japanese Patent Application Laid-open No. 2004-271871    Patent Document 3: Japanese Patent Application Laid-open No. 2006-12722